Author Topic: 5kw Poncelet Wheel Project  (Read 77456 times)

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dbcollen

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Re: 5kw Poncelet Wheel Project
« Reply #270 on: December 17, 2017, 08:03:28 AM »

Replacing the bearings improved the oscillation situation quite a bit. I am still getting swings, but the magnitude is much less. I don't know what normal should be however. I would think the water speed would be constant so the output should be constant.

The oscillations are likely caused by natural turbulence in the river.

SparWeb

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Re: 5kw Poncelet Wheel Project
« Reply #271 on: December 17, 2017, 11:52:06 AM »
Skid,
Have you checked yet to see if the oscillations change with the depth of the wheel?
I have a feeling that when it's 1/2 submerged (water at the axle) the oscillations would go away.
If the oscillations go away when it's that deep, then you can be sure it's torque from blade entry/exit when it's less submerged.
If they are still there, then it's probably something else.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

MattM

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Re: 5kw Poncelet Wheel Project
« Reply #272 on: December 17, 2017, 07:29:57 PM »
dbcollen is probably on to something with natural turbulence.  Water flow oscillates naturally in a river, shifting from literally an infinite number of variables.  At least the pulsing flow should be fairly uniform by the hour.  Surely it's not a huge delta from crest to trough with each pulse? 

One thing that is surprising is that visible wave action on top of the water has almost no effect on what kind of force is provided by the waterflow.  I've actually rode wave crests moving upriver and could feel the resistance shifting rhythmically as I was trying to beat a storm coming in from the south.  Likewise, I've seen crosswind on a river that actually created strange riptides downriver.

Bruce S

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Re: 5kw Poncelet Wheel Project
« Reply #273 on: December 18, 2017, 01:22:09 PM »
Hey All;
Might be a lot late to the party, but is it possible ti's also out of balance? I re-read through the posts and didn't see any mention of a static balance, though the beauty of the this project it's was done and I didn't see the mention.

isn't water also 8x dense as air, and the resulting oscillations magnified as such too?
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Bruce S
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paara

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Re: 5kw Poncelet Wheel Project
« Reply #274 on: December 18, 2017, 11:01:55 PM »
Air is pretty dens where you live ;) you meant 800x ofcourse. Wouldn't the mass of water and metall resist surges. Is it not more likely that it is due to a mppt function in the invertere?Letting the rpm increas over time (minutes) due to small fluctuation in flow, then increasing the resistance/power removed from the system which resultater in a spike of power and slowing og the rotating mass/water wheel. And then repeting itself once in a while. Rpm increase until the mppt reach a certain voltage treshold? If the mppt does not have infinite voltage ofcourse just a thought.

Some new pictures would be great by the way ;) impressive setup you have. Beats solar power hands down.

skid

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Re: 5kw Poncelet Wheel Project
« Reply #275 on: December 19, 2017, 12:09:31 AM »
Might be a lot late to the party, but is it possible ti's also out of balance? I re-read through the posts and didn't see any mention of a static balance, though the beauty of the this project it's was done and I didn't see the mention.

I never did balance it, as I thought it would turn too slow to matter. I did spin it a few times and it would come to rest in different places so it can't be too bad.

Severe out of balance would show as 1x issue, meaning you would see the problem every revolution.

Paara and Rob Beckers have it right I think as it is probably a MPPT issue. I was seeing 200W swings today. Rob's given me some advice on how to download the program, but I haven't done that yet as I'm busy with another project right now.

It's supposed to drop below freezing later this week so I'll try to look at the inverter programming when I pull the wheel out of the water.

keithturtle

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Re: 5kw Poncelet Wheel Project
« Reply #276 on: December 19, 2017, 12:10:58 PM »
I don't know what normal should be however.

You will in time; keep at it.  I love the progress, and the fact that it makes power when the sun doesn't shine

Turtle
soli deo gloria

george65

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Re: 5kw Poncelet Wheel Project
« Reply #277 on: December 19, 2017, 05:17:24 PM »

It's supposed to drop below freezing later this week

It's supposed to go over 40C ( 100F)  AGAIN here today.
How 'bout we help each other out, I'll send you all the temperature you want to keep your river thawed and you send me all the Cold/ snow/ ice you want to offload so I don't cook like an egg every time I go outside.

Reckon if we can work out how to pull this off we are going to be very rich men and you'll be having that water wheel  gold plated!   ;D

MAL

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Re: 5kw Poncelet Wheel Project
« Reply #278 on: December 31, 2017, 12:32:43 PM »
I thought extending the inner lip of the bucket inward with a curl, more like the Poncelet design, to capture more of the energy.  Once the flow  "hits the wall" the  velocity will play a bigger role

Longer blades extending out further will do the same thing I'm hoping. If after adding longer blades and water still pours out the middle of the wheel I will seal the blades off as there is definitely lost energy there.

I was carefully analyzing the wheel's operation yesterday and noticed that the blade slap is actually the water hitting the front of the blade, not the rear. Sounds like the bass drum in a teenagers car stereo. My neighbor says he can hear it when he is near the river.

I think you are on the right track.  Blade design is the issue in my opinion.  A good blade design should enter and exit the water cleanly without disturbing the water any more than necessary.  If your blade is causing a splash of water on entry or plowing water on exit there is room for improvement.  If sound control was the only issue It should be easy to reduce the noise by adding some sort of rubber boot or support...kinda like putting your hand on a drum to deaden the sound, but I believe the sound issue is related to efficiency.  Raising and lowering the wheel also changes blade entry and exit, part of the answer could be in wheel depth.
You may get more speed from having the wheel higher, but you may get more torque by having the wheel lower.